Calculation and Analysis of 220kV Cross-River Cable Carrying Capacity Considering Complex Environments, Part I — Analysis of Thermal Problems for the Entry Section of Overhead Transmission Line to Underground Cable

摘要

Cable temperature rise analysis is a common problem when cables are used in urban power grids. The thermal problem has a high complexity and currently relies mainly on the regulatory method. For more complex conditions, the cable heating problem can be solved by finite element method. However, the difficulties of mesh generation and numerical solution have to be tackled with when using these numerical methods. Whether with the help of commercial software or self-programming to do the calculation, the situation of over-calculation and abnormal results should be avoided. In this paper, a semi-analytical thermal circuit analysis method is proposed to analyze the cable heating problem under complex conditions based on the regulatory approach. The calculation of cable heat generation for complex problems is achieved by considering the heat conduction, convection and radiation effects of different cable arrangement environments in combination with the heat conduction model of the cable sections. On this basis, the super relaxation iterative method is introduced to solve the cable carrying capacity. The results show that this method effectively reduces the computational effort and can be used as a valid method for the analysis of cable carrying capacity in complex environments.